Marker beacon and landing gear controlled throttle engine



June 15, 1943' c, J. CRANE ETAL MARKER BEACON AND LANDING GEAR CONTROLLED THROTTLE ENGINE Filed sept. 2e, 1940 2 sheets-sheet 1 June 15, 1943. C J' CRANE, ET AL 2,321,582

MARKER BEACON AND LANDING GE AR CONTROLLED THROTTLE ENGINE Filed Sept. 26, 1940 2 Sheets-Sheet 2 CARL' J. CRANE RAYMOND K. SToul'.

BYGV'l r TTORNEYS.

atented .Func i5, i

A ,s2-rss2 OFFICE MARKER BEACON AND LANDING GEAR CONTROLLED THBOTTLE ENGINE- Carl J. Crane and Raymond K. Stout, Dayton, Ohio Application September 26, 1940, Serial No. 358,438 2 Claims. (Cl. 244-47) (Granted under the act of March 3, 188'3, as

amended April 30,'1928; 370 0. G. 757) the engine throttle in the closed position. The

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to `us of any royalty thereon.

This invention relates to an automatic enginecontrol system employed in controlling the power plant of an aircraft, particularly during the course of an instrument landing.l

The subject matter of 'this invention may be employed in the blind landing system disclosed in application Serial No. 287,310, iiled July 29, 1939, entitled Aircraft-automatic take off flight and landing, in -the names of Carl J. Crane, George V. Holloman, Raymond K. Stout, and Constantin 'D. Barbulesco, or may be employed in conjunction with the well-known Army Air Corps blind landing system employing two radio compass and associated marker beacon radio transmitting stations aligned with the airport landing runway. In the Army Air Corps system and the system disclosed in the aforementioned application Serial No. 287,310, the control of the aircraft in the vertical plane for such conditions as level flight, rate of ascent or descent, and airspeed, is effected by control of the power output of the power plant. since if the `aircraft is manually or automatically maintained in a level night attitude corresponding tothe night attitude for cruising speed and the power output is kept constant, the aircraft will y at a constant altitude with a constant airspeed, while if the power output of the power plant is increased the aircraft will ascend at a rate dependent on the excess power and conversely, if

the power output is reduced below the cruising speed requirement the aircraft will descend at a substantially constant rate. It is thus possible to control the aircraft in the vertical plane without employing a radio `glide path beam. l

The control system in accordance with the invention comprises a servo mechanism which may be of electric, hydraulic or pneumatic type, which is adapted to normally set the aircraft engine throttle in a position corresponding to a desired cruising (speed, a marker beacon receiver which is a-'aptcg to control the servo device to set the engine throttle in a position such that the aircraft will desc'end in a power glide at a predetermined rate of descent, the marker beacon recever cooperating with a particular ground transmittng station aligned with and located at a predetermined distance from a landing runway and a landing-gear-actuated switch operative on contact of the aircraft with the landing runway to cause the said servo device to position control system also includes a plurality of switches operative to reset the control system and to determine the sequence of operations.

Ihe principal object of the invention is the provision of an aircraft engine control `device including servo mechanism operative to selectively position the engine throttle in any one of a plurality of positions corresponding to definite flight speeds of the associated aircraft, radiosignal-responsive means operative in cooperation with a transmitting station on the ground to cause said servo mechanism to position the engine throttle to cause the aircraft to descend at substantially a constant rate and control means actuated upon contact of the aircraft with the ground to cause said servo mechanism to position the engine throttle in the closed or ,idle position.

A further object of the invention is the provision in a control system for the power plant of an aircraft, of servo mechanism operative to normally maintain the engine throttle in a position to maintain a desired air speed, of a radio receiver responsive to the directional radiation of a transmitter station on the ground and operative within the zone of said radiation to control said servo mechanism to position the engine throttle corresponding to the power gliding speed of said aircraft.

Another object of the invention is the provision in an aircraft power plant control device, of servo means for positioning the aircraft engine throttle in any one of a plurality of predetermined positions, of radio-signal-responsive means operative to cause said servo means to` position said engine throttle in one of said predetermined positions corresponding to a predetermined aircraft gliding speed and ol? means responsive to the contact of the aircraft with the ground for causing said servo means to position said engine throttle in another of said predetermined positions corresponding to the idle speed oflsaid power plant.

A further object of the invention is the provision in apparatus of the character described of a means responsive to the air speed of an aircraft operative to vary the power output of the aircraft engine to maintain the air speed substantially constant at a predetermined cruising speed and radio-signal-responsive means operative to vary the setting of said air-speed-responsive means to control the power output of said engine, to maintain a substantially constant gliding speed.

Other objects not speciiically enumerated above will become apparent by reference to the detailed description in the specication and the appended drawings in which:

Fig. 1 is Va diagrammatic sketch illustrating the sequencel of operations of the engine throttle control during the course of an instrument landi118;

Fig. 2 is a view illustrating the elements of the aircraft engine throttle control mechanism;

Fig. 3 is a detail view partly in section illustrating the landing-gear-operated switch; and

Fig. 4 is a view illustrating the details of the relay controlled by the marker beacon radio receiver.

Referring now to Fig. l, if it is assumed that,

the aircraft I' is flying along the ight path A directionally aligned with a landing runway, the

A engine throttle will be governed by control mechanism, generally indicated by the reference numeral 3, in accordance with the invention, so that it will approach the plane of the vertical radiation of a marker beacon radio transmitter 2 of well-known type, at a substantially constant air speed corresponding to a desired preselected cruising speed. When the airplane I passes into the plane of the marker beacon transmitter radiation R at point B, the marker beacon receiver antenna H22 on airplane I transmits the marker beacon signal to a marker beacon receiver "I2Il connected thereto, which receiver--among other things-is operative to close a. relay, which in turn causes the throttle-control mechanism to change the throttle setting from cruising to glide position, the airplane I then descending along the glide path G at substantially a constant rate of descent. Upon the airplane landing gears contacting the runway as at C, a switch vcontrolled thereby causes the throttlecontrol mechanism to position the engine throttle in the "idle running position. The details of the novel throttle-control mechanism illustrated in Figs. 2 to 4 inclusive and hereinafter referred to by the term throttle engine as used in the art, will now be described.

Referring now to Fig. 2, the throttle-control mechanism, or throttle engine, indicated by the reference numeral 5 in Fig. `l is shown as adapted to control an aircraft engine indicated by the reference numeral I0. The engine I0 is provided with the usual carburetor II having a throttlecontrol valve I2 actuated by a throttle-control lever I3. The throttle-control lever I3 is connected to a reciprocable pistpn rod I4 of a hydraulic servomotor generally indicated by the reference numeral I5. 'I'he servomotor I5 is of .engine-driven vacuum pump,

Ythe bellows device 2i) toward the right.

f the movable portion 3l of the bellows. lows 32 is connected by means of a conduit 33 a well-known type operated by oil under pressure f supplied from the engine oiling system. The servomotor is adapted to be cotrolled by a conventional pilot valve (not shown) which in turn is actuated by the valve rod I6. The valve rod I6 is pivotally connected at its outer end to a floating lever Il between the ends thereof. At

-its lower end the oating lever I'I is pivotaily The bellows device 20 comprises a pair of opposed metal bellows 2| and 22 respectively, which are respectively connected by means of conduits 24 and 2.5 to a pilot control valve body 26. Each of the bellows is also connected to the atmosphere by means of needle-controlled bleed valves 23. The pilot valve body 26 is provided with a conduit 21 which is adapted to be connected to an or other convenient vacuum source (notshown). The pilot valve body 26 has reciprocably mounted therein a pilot valve 28 which is adapted to control the communication between the vacuum conduit 2l and the conduits 2li and 25 respectively. In the position as shown in Fig. 2, the pilot valve 23 allows an equal reduction in pressure in the conduits 2d and 25, which will cause no resulting .deflection of the bellows device 20. If, however,

the pilot valve 28 is moved upward from its neutral position, communication between the vacuum conduit 2l and the conduit 25 will be restricted, permitting a greater reduction in pressure in the bellows 2i, causing a deflection' of This deiiection of the bellows device 2li causes a clockwise rotation of the floating link II about its lower pivot, causing the pilot valve rod It of servomotor I5 to be moved to the right. This motion of the pilot valve rod I6, in turn, will cause a displacement of the servomotor piston toward the right an amount proportional to the displacement of the valve rod I6, the follow-up link Iii restoring the pilot valve of servomotor I3 to its neutral position after the piston rod I Il has opened the engine throttle an amount proportional to the displacement of control rod Iii Aand pilot valve 28. Similarly, a downward movement of the pilot valve 28 will cause a movement of the servomotor piston rod I4 to the left, as seen in Fig. 2, causing a proportionate closing of the throttle valve I2.

The pilot valve 28 is pivotaily connected to one end of a lever 29, the other end of which is connected by means of a link 3i) to the movable portion 3i of a bellows 32, the pilot valve thus moving an amount proportional to the deection of The belwith a Venturi tube 34 adapted to be mounted on an airplane I (Fig. 1) so as to be exposed to the air stream. The movable portion 3| of the bellows 32 is adapted to be connected t the lower able element 3| of the bellows 32 is provided with an extension arm 35 which is adapted to be connected by means of a link 36 to the piston of an adjustable air dashpot 31. If the bell crank 4I is held stationary and a predetermined tension is placed on a control spring 38 by means of the terminal rod 39 and the adjusting nut 40, the upper movable portion 3| of the bellows 32 will be deflected upward, causing a simultaneous downward movement of the pilot valve 23 an amount suilicient to cause the servomotor I5 to move the throttle valve I2 of engine I Il to the wide-open position. As the aircraft increases in speed, the suction effect created by the Venturi tube 34 will be sufficient to cause a downward movement of the upper portion of the bellows 32 until the force acting on the bellows due to the reduced pressure' produced in conduit 33 is just suilicient to balance the loading of the control spring 38 as determined by the adjusting nut 40. In this balancedposition the pilot valve 28 will be returned to its neutral position and the throttle I2 Soi engine Il will be moved to a position corresponding to a desired 4cruising speed of the aircraft, this cruising speed being determined by the initial loading of the spring 38. The elements I4 to 48, inclusive, form the structure of. a well-known throttle-control device incorporated in the "Sperry automatic pilot and disclosed in greater detail in United States Patent No. 2,160,194, granted to Mortimer F. Bates, the structure of which per se forms no part of the invention claimed herein.

An electric motor 50 is mounted adjacent the extension 35 of the bellows 32; and the shaft 5I thereof is provided withy a cam 52 adapted, in the position shown in Fig. 2, to remain out of contact with the extension arm 35 oi' the bellows. When the motor 50, however, rotates the cam 52 into a position 180 from the position indicated in Fig. 2, the high part of the cam will engage the extension portion 35 of the bellows 32, forcing the bellows to collapse, thereby causing an upward movement of the pilot valve 28 an amount sumcient to actuate servomotor I5 to move the engine throttle I2 to the closed, or idle position. It is thus seen that the cam 52 serves as a means to ductor 51 to the motor 5l, the other connection 58 thereof being suitably grounded to the negative terminal of a power source. The contact actuated by the control arm 55 is adapted to engage either of a pair of contacts (not shown) respectively connected to the conductors 50 and 52. The conductor 60 is electrically connected to a contact point 6I of a switch generally indicated by the reference numeral 66, and the conductor 52 is similarly connected to a contact point 53 of the switch. A third contact point 64 of the switch 66 is electrically connected by means of conductor 61, landing-gear-actuated switch 15, and conductor 61 to a conductor 68 electrically connected to the positive terminal of a direct current battery indicated by the reference numeral 10, the negative power supply terminalv 58' of the battery 1li being suitably grounded, all conductors which connect to the negative terminal of the battery being similarly indicated by theconventional ground symbol. The switch 56 is provided with a double-arm switch blade 55 which is adapted to be manually actuated into either of two positions.

The landing gear switch 15, as seen in Fig. 3, comprises a cylindrical casing 'i5 which has mounted therein an expansible metal bellows 11, the motion of which is opposed by a control spring 18. Any outward movement of the bellows 11 will cause the follower rod 15 to cause a closing of the electrical contacts 85 to complete an electrical circuit between the conductors B1 and 61'. The expansible metal bellows 11 is connected by means of a exible high-pressure conduit 8i to the cylinder 82 of a conventional aircraft landing gear shock strut which is provided witha piston rod 83 having a conventional stub axle B4 mounted at right angles thereto on its lower end. The stub axle 84 serves as a mounting for the landing gear wheel 85.

When the aircraft I (Fig. 1) is on the ground,

there will be suiilcient iluid pressure developed in the conduit 8| to cause the expansible bellows 11 to expand upward against the resistance of the spring 18 an amount suiiicient to cause a closing of the resiliently mounted contacts 85, thus completing the electrical circuit between the conductors 81 and 51', as previously described. Whenthe airplane leaves the ground, the piston rod 83 of the shock strut will move downward, relieving the fluid pressure within the cylinder of the shock strut and the expansible metal bellows 11, causing spring 18 to force the bellows downward to release the engagement between the contacts 8l .-and, consequently, opening the velectrical connection between the conductors 81 and 51'.

Referring again to Fig. 2, if it is assumed that the cam -52 is in a position 180 from the'position shown in Fig. 2, the switch arm 55 will be in its ,extreme position to the left of theposition shown circuit being completed by motor conductor 58 t0 the negative terminal of battery 10. The motor 55 will then rotate in a clockwise direction until the cam 52 is in the position as shown in Fig. 2. the linkf54 having in the meantime moved switch arm 55 to the extreme right position, as seen in Fig. 2, interrupting the supply of power to the motor 50 and stopping the motor with the cam 52 out of engagement with the extension arrn35 oi' the .bellows 32. Thecontrol spring 38 will then be operated to open the engine throttle to the wide-open position, and Venturi tube 34 will be operative to return the throttle to the cruising speed position after the airplane takes oil. from the ground and acquires an air velocity suflicient to create a reduced pressure within bellows 82 to counterbalance the loading ofspring 38 in the manner previously described. The Venturi tube 34 during ight will then be operative to main-` tain the airplane engine throttle in a position such as to maintain the speed of the aircraft substantially constant, since any increasein speed above the preselected cruising speed will cause an increased vacuum within the bellows 32, which will in turn cause a suilicient closing of the engine throttle to again return the air speed to the predetermined value. Similarly, ii' the speed of the airplane should decrease below the predetermined cruising speed, the pressure within the bellows 32 will begin to approach atmospheric pressure, allowing the control spring 38 to move the upper portion of the bellows 32 in an upward direction, causing pilot valve 28 to move downward with a consequent opening of the throttle valve I2 an amount suilcient to restore the aircraft speed to the preselected cruising value. After the airplane is in the air the pilot can manually rotate the switch blade 65 into a posisubstantially constant. However, upon the aircrafts contacting a landing runway, suilicient iiuid pressure will be,built up in the conduit 8| (Fig. 3) to cause the contacts 80 of the landing gear switch 15 to be closed, completing a circuit from battery 10, conductor 68, and conductors 81 and 61 in series with switch 15 to the switch` contact point 64 of switch 65. Current will then iiow to switch contact 6| and conductor 6,0 to the motor conductor 51, causing the motor 50 to be energized and to rotate in a clockwise direction until cam 52 depresses the extension arm 35 of bellows 32 in a downward direction a sufficient amount to cause the pilot valve 28 to control the servomotor I5 to move the throttle to the closed, or idle position. The position of cam 52 will then be 180 from the position as shown in Fig. 2, and link 54 will move the switch control arm 55 of the switch 56 to the extreme left position, interrupting the supply of power from conductor 60 to the conductor 51, thus de-energizing the motor 50 and leaving the cam 52 in the abovenoted position.

In order to change the loading of vthe control spring 98 an amount suillcient to cause the throttle engine to change the throttle setting from the cruising position to the gliding position, the bell crank previously noted as serving as a support for the upper end of the spring 88, has one of its arms connected to a link 92 which is eccentrically pivotal as at 93 to a crank disk 94| mounted on the ends of the armature shalt 95 of an electric motor 96. The outer end of the link 92 is connected to the switch arm 91 of a follow-up switch 98, identical in construction with the previously described switch 55 and functioning in a similar manner. The switch arm 99 carries a contact (not shown) which is electrically connected by means of conductor 99 to supply current to the motor 96, the other motor lead |00 being suitably grounded to the negative terminal of the battery 10. 'Ihe contact carried by the switch arm 91 is adapted to engage a contact (not shown) electrically connected by means of conductor 0| to the switch point |02 of a manually controlled switch |01 similar in construction to the previously vdescribed manually controlled switch 66. The contact carried by the switch arm 91 is also adapted to engage a contact (not shown) electrically connected to a conductor |00' which in turn is serially connected through a time-delay relay 0 to the conductor |04, which in turn is connected to the switch contact point |03 of the switch |01. A third contact |05 of the switch |01 is connected to the positive power supply lead 68 of the battery 10. The switch |01 is provided with a double arm switch blade |06 adapted to be moved in two positions so as to electrically connect switch point with either of switch points |02 or |03.

The time-delay relay |0 is connected by means of the output terminals ||8 to a marker beacon radio receiver |20 of well-known type, which is connected by means of the leads |2| to the an- The relay arm ||2 is provided with a switch contact ||5 which is adapted to engage a yleldingly mounted contact ||6 whenever the relay arm ||2 is attracted by the core of the relay coil contacts 5 and ||5 are respectively connected to 'the conductors |04 and |04 and adaptedto complete an electrical circuit between these conductors when engaged. The relay arm ||2 when sufficient intervalof time to insure the necessary` operation of the electric motor 96.

Referring again to Fig. 2, if we assume that the aircraft is on the ground and it is desired to apply tension load to the control spring 38 to attain a desired preselected cruising speed, and assuming that the crank disk of motor 96 is in a, position from that shown in Fig. 2, the arm of bell crank 0| supporting the upper spring terminal 39 of the spring 38 will be moved downward, releasing a portion of the tension loading on the spring 30. If then the switch arm |06 of switch |01 is moved to a position such that the switch contact points |02 and |05 are interconnected, current may then flow from conductor 68 to conductor |0| and-conductor 99 by means of the associated contacts of follow-up switch 98, the switch arm 91 at this time being in a position to the extreme left of that shown in'Fig. 2. Motor 95 will then be energized to rotate in a clockwise direction into the position shown in Fig. 2. switch arm 91 interrupting the flow of current fromthe conductor |0| to conductor 99. The link 92 will then move to the right into the position shown in Fig. 2, elevating the adjustable spring terminal 39 of the control spring 38, applying a tension load to the `spring 38 corresponding to the desired cruising speed loading determined by the adjustment nut.

40, as previously described.

After the aircraft is in the air, the pilot rotates the switch blade |06 into the position, as shown in Fig. 2, interconnecting switch contacts |03 and |115. Upon the markerbeacon antenna |22 receiving a signal from the marker beacon transmitter 2 (Fig. 1) the marker beacon receiver |20-among other things-will cause relay ||0 to be closed in the manner previously described with reference to Fig. 4. Current will then flow from conductor 68 to conductor` |04, through timedelay relay ||0 to conductor |04 through the contacts of switches 98 to motor lead 99, energizing the motor 96 for a suiiicientlength of time due to the time-delay feature of relay l0, as previously mentioned, to cause the crank disk 94 to be rotated in a clockwise direction 180 from the position as shown in Fig. 2. The arm of bell crank 4| supporting the spring terminal 39 will then move downward an amount sulcient to re- 'l'ase the tension load of spring 38 to the loading value corresponding to the glide condition of the engine throttle, l2. 'Ihisrelease of loading on the spring 38 allows the suction produced by Venturi tube 34 to cause a partial collapse of the bellows 32, which in turn will shiftthe pilot valve 28 upward an amount sufficient to cause the servomotor I5 to position the engine throttle |2 in the power gliding position. The aircraft then proceeds along the glide path G ln-the manner pre viously described with reference to Fig. 1.

The manual control switches 66 and |01 can Thel by me lns of the above-described control system. a low the aircraft to take oil' under auto may matic control until the aircraft reaches a. desired manner previously described, the electrical circuits associated with the motor t@ are conditioned so as to be effective in conjunction with the landing-gear-operated switch l to bring the engine throttle to the idling speed position upon contact of the landing gear with the landing runway. lt is also seen that after the aircraft is in the air the pilot by means of the switch i071 may condition the circuits associated with the switch so as to cause the throttle engine to automatically change the throttle setting from the cruising speed position to the glide speed position upon the marker beacon receiver H actuating relay H0, permitting the aircraft to descend at a substantially constant rate of descent, its air speed during the descent being controlled by means ofl the Venturi tube Sii and bellows 32 in the manner previously described. the sequence of the various above-described operations occurring in the manner described above with reference to Fig. l. Y

- Where a. plurality oi' aligned marker beacon transmitters are employed in an instrument landing system of which the present invention forms a part, it is desirable that the relay H0 be actuated by a signal received from the far marker beacon transmitter, i. e., the transmitter located nearest the landing runway. This operation can be easily secured by having the radiation oi' 'cruising speed. By then setting switch t@ in the the far marker beacon transmitter modulated at some selected frequency and by having the output of the marker beacon receiver fed to a nlter circuit adapted to separate out the particular modulation frequency for operating the relay IIB, this means for operating a. control by the radiation of a particular marker beacon transmitter being well known and disclosed in United States Patent 2,133,285 granted to Francis W. Dimmore. n

While a hydraulic type of throttle engine has been illustrated in the drawings, it is apparent that electric or pneumatic servomotors may be employed instead, one example of the application of marker beacon and landing gear switch-control means to an electric servomotor operative to position the engine throttle in various preselected positions being described but not claimed v in copending/application Serial No. 348,720, tiled July 31, 1940, in the names of Carl J. Crane. George V. Holloman, and Raymond K. Stout and entitled Electric throttle control."

While one embodiment of the invention has been illustrated and described, other modications will become apparent to those skilled in the art as falling within the scope of the invention as dened by the appended claims.

' We claim:

l. In a system for controlling an aircraft in the vertical plane by controlling the power output of the engine for propellingthe aircraft, the combination with said engine of; an enginespeedcontrolling means; a throttle engine operative to position said speed-controlling means in a plurality of predetermined positions, certain of said positions corresponding to the cruising, gliding, and idle speeds of said'engine, respectively; means for causing said throttle engine to position said speed-control means in a prede-` termined cruising speed position; radio-signalresponsive means operative to cause said throttle engine to move said speed-control means from the cruising position to the gliding position, whereby said aircraft descends at a substantially constant rate; and means responsive to the contact of said aircraft with -the ground to cause said throttle engine to change the position of said engine-speed-control means from the gliding position to the idle speed position.

2. In an airspeed control for an aircraft, an engine, means for controlling the speed of said engine. an airspeed responsive governor connected to/said speed-control means to control 4the speed of said engine to maintain a substantially constant preselected airspeed, said governor including a pressure responsive element, a servomotor responsive to movement of said element and operatively connected to said speed control means, a governor modiiler including a resilient element yieldingly opposing movement o! said pressure reponsive means in one direction, means for loading said resilient elementso that said pressure responsive element is eil'ective to regulate the power output of said engine to maintain one particular value ot the airspeed, radio signal responsive means eiIec-tive to vary the loading of said resilient element by a predetermined amount to render said pressure responsive means eilective to control the power output of said engine to maintain a din'erent predetermined aix-speed, power means for rendering said governox` modifier ineffective and to control said servomotor to position said speed control means in the idling speed position, a landing gear actuated means for controlling the actuation of said power means, and manually actuated means for renderingl said landing gear actuated means operative or inoperative to control said power means.

CARL J. CRANE. RAYMOND K. STOUT. 

